Circuit controlling device



June 19, 1934. R ET AL 1,963,760

CIRCUIT CONTROLLING DEVICE Filed Jan 13, 1933 5 Sheets-Sheet l ATTORNEY n 1934- R. R. PITTMAN ET AL 4 1,963,760

CIRCUIT CONTROLLING DEVICE Filed Jan. 15, 1953 3 sh et -sheet 2 NTO f w. (Wan ATTORNEY June 19, 1934.

R. R. PITTMAN ET AL CIRCUIT CONTROLLING DEVICE Filed Jan. 13, 1933 3 Sheets-Sheet 3 WWW BY MAM ATTORNEY Patented June 19, 1934 PATENT OFFICE,

CIRCUIT CONTROLLING DEVICE Ralph R. Pittman and Carroll H. Walsh, Pine Bluff, Ark.

Application January 13, 1933, Serial No. 651,567 13 Claims. (01. 200-146) This invention relates generally to means for the control of electric distribution and transmission line circuits, and particularly to circuitcontrolling and circuit-interrupting devices for this purpose.

In Patent No. 1,937,166 issued Nov. 28, 1933 to Pittman there is described a means for extinguishing transmission line arcing faults by the use of devices which reduce but do not inter rupt the current in the line conductors. It is an object of this invention to provide means which may be used in connection with the above mentioned invention, and in addition to provide a positive open-circuit position for definitely disconnecting a circuit in case a line-fault thereon is not of a transitory nature.

An additional object is to provide a high speed circuit-reclosing device for the purpose of interrupting or controlling the line current in a faulty transmission line to extinguish an arcing fault thereon, such as might be caused by lightning, in a sufiiciently brief interval of time to prevent serious inconvenience to the users of electrical energy supplied through the line.

A further object is to provide means for establishing an are having a very high voltage gradient in terms of volts per unit length of are within a contact structure having a' plurality of closed circuit positions.

A further object is to provide means whereby a progressively increasing current-limiting resistance is introduced in the circuit-controlling device in its movement from one closed circuit position to another.

A further object is the provision of means whereby the cross-sectional area of the arc path through the device when in a circuit-opening position-is controlled by the magnitude of the current in the arc path, so that the voltage gradient through the device will tend to be independent of the current therethrough.

A yet further object is the provision of means for setting up a high resistance arc-path within an arcing contact structure, and for immediately thereafter entirely disconnecting the arcing contact structure from the circuit.

An additional object is the improvement generally of circuit interrupting or controlling devices.

With the above and other objects in view which will appear as the description proceeds, our invention resides in the novel features of form, construction, arrangement and combination of parts hereinafter described and pointed out in the claims.

In the accompanying drawings (3 sheets)- Figure l is a front elevational View of the essential parts of a circuit controlling device embodying our invention, shown in a. closed circuit position and illustrated partly in section. v

.Figure 2 is a fragmentary illustration of the device shown in Figure 1, shown in an open circuit position, and also illustrated partly in section.

Figure 3 is a sectional view of the arcing contact structure of the device, taken approximately on the plane 33.

Figure 4 is an end elevational view of the main contact structure of the device.

Figure 5 is a fragmentary sectional View of the main contact-carrying insulating bar, taken approximately on the plane 5-5.

Figure 6 is an elevational view of the invention, showing particularly the housing for the device.

Referring now more in detail to the accompanying drawings, and particularly to the embodiment of our invention illustrated by Figure 1, 10 is a fixed portion .of a housing 59 for the device, only the portion necessary for supporting the assembly of the contact structure being shown for convenience in Figure 1. The substantially square shaped hollow member 11, of any metal of suitable physical characteristics, is rigidly fixed to the housing 10 by means of the cap screws 14, the latter extending through laterally-extending ears 13, which are preferably made integral with th member 11.

The insulating supports carry the stationary portions of the arcing contact structure, and are rigidly fixed to the inner sides of opposing walls of the member 11 by means of the bolts 12, and extend in a downward direction substantially'nor-- mal to the plane of the housing portion 10. A pair of opposing blocks of insulating material 44 are supported by the insulating supports 55 by means of the bolts 37 extending loosely through and normal to the plane of the supports 55, and arranged to cooperate with tapped holes in the blocks, and locked rigidly in place with the nuts 39. The springs 45 are arranged to urge the blocks 44 together, this movement being limited by the adjustment of the bolts 37 in the nuts 39, with the result that the blocks 44 are free to move laterally outward from each other against the bias of the springs 45, bpt cannot move inwardly toward one another beyond a distance controlled by the adjustment of the bolt 37.

For convenience in guiding the movement of the cooperating movable member, later herein described, the adjacent surfaces of the insulating blocks are made substantially in the shape of a flat bottom V. Extending through openings normal to the plane of the flat central portion are the stationary arcing contacts 48, biased toward each other by means of the arcing contact springs 47. To provide for flexibility of the contacts 48, and for shunting the contact springs 47, the flexible copper braids 49 are provided, having one end -thereof soldered to the arcing contacts 48 and the other end rigidly secured to the metal members 34 by means of the screws 50. Two pairs of the contacts 48 are shown in this embodiment, the two contacts positioned in axial relation forming a pair, and the axis of one pair positioned vertically above that of the other.

The metal members 34, above mentioned, are rigidly fixed to the inner face of the insulating supports 55 by means of the cap screws 35, and extenddownwardly from the screws 50 to a point below the lower end of the insulating blocks 44. At this point, the ends of the members 34 are bent inwardly one toward the other at substantially a right angle with the major portion of the members 34, the bent portions thus affording a pair of horizontal flat surfaces adapted for cooperation with a pair of resilient contacts.

Adapted for reciprocatory movement within, and guided in its reciprocations by, the opposing insulating blocks 44 is the movable member of the arcing contact structure, shown more in detail in Figure 3, of such size and contour that it substantially fills the space between the spaced blocks 44. As indicated, this movable member is made up of a pair of insulating blocks 43, arranged to laterally extend from a central substantially rectangular block of insulating material 56, the three portions being rigidly held together by the metal bands 40, and the fastening screws 41 extending through the bands 40 into the control rod 33. A hollow portion within the assembly of the movable member of the arcing contact structure is provided for mounting the movable metallic contacts 52, positioned adjacent the midpoint of the movable member and biased outwardly one from the other by the spring 53. The copper braid 54 is for the purpose of shunting the spring 53 to prevent damage to the spring due to thermal effects of the current which may pass through the contact structure.

The insulating control rod 33 has rigidly mounted thereon the movable member of the arcing contact structure by any suitable means as by the metal bands, 40 and the screws 41. It will be apparent that, upon vertical movement of the control rod 33, the movable contacts 52 may be brought into aligned engagement with either the upper or the lower pair (7f the resiliently mounted contacts 48, or may be caused to travel in a downward direction below the lower pair of the contacts 48.

We will now describe the means provided for connecting or disconnecting the arcing contact structure. The insulating entrance bushings 15, only partly shown, form an insulating housing of porcelain or other suitable material for the conductors 16 extending therethrough, and are rigidly supported in any suitable manner (not shown). Near the lower end of the bushings 15 are mounted the contractible adapters 17, each having an internal threaded opening for cooperating with threads on the lower portions of the conductors 16. The adapters 1'7 are further provided with an additional downwardly depending portion having opposing flat parallel sides, and a pair of horizontally spaced holes are drilled and tapped normal to the plane of the sides. The

main contact fingers, illustrated more in detail by Figure 4, are rigidly supported by the cap screws 19, extending through a pair of holes in alignment with the above mentioned tapped holes in the adapter 17, and include a pair of opposing spaced metal contact shoes 57 for cooperating with the contact springs 58. The contact shoes 57 are arranged in spaced relation, and have inwardly sloping and curving portions at the lower extremities thereof to form an inwardly guiding flare for the entrance of a cooperating contact mem-- her. The opposing faces of the contact shoes 5'7 above the entrance flare are arranged to slope upwardly, and outwardly from each other.

For cooperation with the stationary portion of the main contact of the device, we provide an insulating bar 29 having cooperating contact members 21 of copper or other suitable metal rigidly attached thereto by the bolts 28. The member 21 is arranged to snugly fit within the space between the contact shoes 57, and for this purpose and as shown in Figure 4 is provided with an enlarged upper portion having a concave upper surface and inwardly and downwardly sloping opposing sides. It will be apparent from the description here recited that the insulating bar 29 with the contacts 21 rigidly attached thereto, will be held in a contact making position by the bias of the springs 58 against the contact shoes 57. It will also be apparent that a downward movement of the insulating bar 29 will cause the movable contact members 21 to be disengaged from their cooperating contact shoes 57.

The movable main contact members 21 are provided with inwardly disposed portions having a pair of upper horizontal surfaces near the top of the insulating bar 29. To these upper surfaces are attached the upwardly disposed resilient auxiliary metal contact brushes 30 by means of the cap screws 31, these contact brushes being arranged to engage the inwardly bent portion of the metallic members 34 when the main contacts 21 are seated within the main contact shoes 5'7. It will be seen that a downward movement of the insulating bar 29 not only disengages the main contacts, but also, through the downward movement of the auxiliary contact brushes 30, simultaneously effects the disconnection of the arcing contact structure.

In addition to the upper surfaces of the inwardly extending portion of the movable main contact members 21, we have also provided similar horizontal surfaces near the bottom surface of the insulating bar 29, for the purpose of rigidly attaching thereto the downwardly disposedshunting resilient metal contact brushes 24 by means of the cap screws 25, and the bent washers 26. For cooperating with the shunting contact brushes 24, the metal bar 22 is rigidly secured to the lower extremity of the operating rod 33 by means of the bolt 23, and has a fiat upper side for engaging the shunting contact brushes 24. Obviously a downward movement of the operating rod 33 will cause the metal bar 22 to disengage the shunting contact brushes 24.

The operating rod 33 of maple wood or other suitable insulating material extends in a vertical direction through an opening near the midpoint of the insulating cross bar 29, the opening being somewhat larger in section than the rod to provide annular space for the walls of the sleeve 32. A flanged upper portion of the sleeve 32 prevents its downward passage through the opening in the insulating cross bar 29, while the opening through the sleeve 32 itself is somewhat larger than, the

' portion of the sleeve 32.

cross-section of the rod, so that the operating rod 33 may freely reciprocate through the sleeve 32. As shown in Figure 5, the operating rod 33 and the sleeve 32 are rectangular in section to prevent rotation of, and consequent contact misalignment by, the cross bar 29.

The metal collar 36 is rigidly fixed to the operating rod 33 adjacent the lower end of the movable portion of the arcing contact structure and is adapted, upon a definite downward movement of the operating rod 33 to engage the top flanged For this purpose, the metal collar 36 is of somewhat larger diameter than the opening through the sleeve 32. By this means, upon a definite downward movement of the operating rod 33 the insulating cross bar 29 is urged in a downward direction, resulting in the disengagement of the main contact members 21 from their co-operating resilient stationary contact shoes 57.

It will be seen that our circuit controlling device comprises a main disconnecting switch in cluding the cooperating members 20 and 21; a main current carrying switch including the cooperating members 22 and 24; an auxiliary disconnecting switch including the cooperating members 30 and 34; and an arc suppressing switch including the cooperating members 48.

and 52.

In the initial normally circuit-closed position shown by the dotted lines in Fig. 1, the arc suppressing switch is serially connected through its upper pair of contacts with the auxiliary disconnecting switch; the series arrangement of the latter switches is shunted by the main current carrying switch, and the group comprising the last-named three switches is in series circuit relation with the main disconnecting switch.

Following a first downward movement of the control rod 33, the relation of the switches to the circuit is indicated by the broken lines in Fig. 1. In this position, the circuit is completed through a serial arrangement consisting of the main disconnecting switch, the auxiliary disconnecting switch and the lower contacts of the arc suppressing switch, since the insulating bar 29 in this position is supported by the cooperating con-; tacts of the main disconnecting switch, and the main current carrying switch has been moved to the open position.

A second downward movement of the control rod 33 places the switches in the position shown in Fig. 2, in which all of the switches are open. It will be seen that in this position all of the elements constituting the arc suppressing switch, the main current carrying switch and the auxiliary disconnecting switch are completely isolated from both terminals of the device, thereby not only preventing damage from leakage current to the insulating material employed in the arc suppressing switch assembly, but also pro-, viding six breaks in series to effectively open the circuit.

In the initial normally circuit-closed position the path of the current through the device is into one of the conductors 16, through a first main contact structure, thence through the shunting contact bar 22 via the contact brushes 24, to the second main contactstructure, and to the other of conductors 16. Aportion of the current may pass through the arcing contact structure through the engaged contacts 30-34, and 52 48, but as will shortly appear, this in no way affects the operation of our device. The position of the movable members of the device for the current path just described is illustrated by the solid lines in Figure 1.

The broken lines in Figure 1 illustrate the position of the movable members of the device following the first downward movement. It will be clear that this movement has resulted in the downward movement of the metal bar 22 away from the cooperating. brushes 24, and that the contacts 52 have moved in a downward direction to engage the lowe'r pair of arcing contacts 48. The path of the current when the device is in this position is therefore entirely through the arcing contacts 5248, as the insulating bar 29 effectively prevents the passage of current thereacross.

Figure 2 illustrates the position of the movable members of the device following the second downward movement of the operating rod 33. It will be observed that the bollar 36 has now moved a suflicient distance to engage the upper fianged portion of the sleeve 32, thus urging in a downward direction the insulating bar 29 and the movable main contact members 21. Upon a downward movement of the insulating cross bar 29, the auxiliary contact brushes 30 are moved downwardly away from the cooperating auxiliary contact members 34, with the result that the arcing contact structure and the arcing contact structure shunting arrangement is entirely and completely disconnected from the circuit.

Bearing in mind that electric transmission and distribution line faults are of two classes, the first due to instantly disappearing or transitory causes, as might be caused by a lighting discharge, and the second of a longer duration, as due to a failure of insulation or a broken conductor, we will now explain the operation of our circuit controlling device, when connected to a circuit to be controlled.

The purpose of reclosing the circuit through 115 the lower contacts of the arc suppressing device is to reduce the time of outage of a connected circuit, following the removal of a temporary circuit fault by the first downward movement of the control rod. In the absence of these lower 120 contacts, the circuit would be disconnected through that period of time necessary to reverse the movement of the movable parts of the device, which period is an appreciable percentage of the total time required for the complete down and up motion. The switching device herein described provides means for maintaining the circuit in closed position during the time necessary to reverse the direction of motion of the moving parts, thus causing two short interruptions having a total time less than the one long interruption which would otherwise result. In addition, the reclosure at the lower position of the are extinguishing device permits synchronous apparatus to become stable before the second interruption occurs.

Immediately following the operation of any suitable fault-responsive means, a first downward movement of the operating rod occurs as explained above. While the movable arcing contacts 52 are sliding across the resiliently mounted arcing contacts 48, the shunting bar 22 is disengaged from the cooperating shunting contact brushes 24. The entire current through the device is in this manner caused to pass through the arcing contact structure, and as the movable arcing contact members 52 separate from the upper pair of resiliently mounted arcing contact members 48, a circuit-interrupting arc is drawn therebetween, and in the space and along the ad- 150 jacent surfaces of the insulating blocks 43 and 44. It is now well known that an arc path within a restricted space between the surfaces of a pair of insulating bodies has a voltage gradient controlled by the dimensions of the arc space, and we employ this principle in our device by making this are space as small as possible in width, with the result that an exceedingly high voltage gradient, of the order of 10,000 volts per inch in air, and 25,000 volts per inch in oil, is obtained. A very high resistance current-limiting arc isthus set- ,up and elongated within the arcing structure of our device, and only a small length of arc path is required to limit the current to such a small value that an arcing fault on the connected circuit will become unstable, and be extinguished. With the voltage gradients above mentioned, it will be seen that an arc path within the arcing contact structure of our device need be only about one inch in length for application to a circuit operating at 13,000 r. m. s. volts. This is an important consideration, because such a relatively small movement may be accomplished in a short time of the order of 2 to 5 cycles on a 60 cycle alternating current circuit, with the result that the time required for extinguishing an arcing fault on a connected circuit is much less than that required by any circuit controlling device now available. Immediately following the extinguishment of any arcing fault or faults which may have existed on the connected circuit, the arcing contact memhere 52 engage the lower pair of stationary arcing contact members 48, for reclosing the circuit.

Following this operation, the circuit-controlling device is immediately restored to the initial normally circuit-closed position, as explained above.

Having explained the operation of our circuitcontrolling device in connection with arcing faults due to instantly disappearing causes, we will now describe its operation with reference to faults of a more permanent nature, such as might be caused by a fallen conductor. Starting from the normally circuit-closed position, the first operation is as described in the paragraph next above. If, however, this operation does not clear the connected circuit of faults, the fault responsive means permits a second downward movement of the operating rodto occur. Again in this case the circuit-interrupting arc is elongated between the movable blocks of insulating material 43 and the resiliently mounted blocks 44 as the movable arcing contacts 52 separate from the lower pair of resiliently mounted arcing contacts 48, in a manner similar to that described in connection with the first movement of the operatingrod. Immediately following the stretching of the circuit-interrupting arc in this manner, the metallic collar 36 engages the upper flanged portion of the sleeve 32, urging the insulating cross bar in a downward direction, and thus entirely and completely disconnecting the arcing contactstructure from thecircuit.

We will now explain our reasons for providing means for completely disconnecting the arcing contact structure from the circuit. While our device will operate as herein described with many well-known insulating materials having proper physical characteristics, we prefer, for reasons of economy to use a fibrous material, such as vulcanized fiber. If the device is operated with oil as a dielectric, we have found that a surfacedeposit of carbon, due to the action of the heat of the arc, may form on the surface of the insulating blocks subjected to the arc. Such a coating of carbon is a high resistance conductor of electricity, and while it does not prevent the operation of the device as herein described, it does not permit a complete isolation of the connected circuit unless some provision is made to completely disconnect the arcing contact structure. In addition, a certain amount of moisture is present in most commercial forms of fiber, and this moisture may cause a certain amount of leakage current to pass through the contact structure provided it is not entirely isolated in the opencircuit position. It will be apparent that in the case of the use of either air or oil as a dielectric, any possibility of leakage current through the arcing contact structure is effectively prevented by the arrangement we have provided in our device.

Referring further to the arcing contact structure of our device, we wish to point out the means provided for controlling the voltage gradient of the circuit-interrupting arc. The springs 45 are constantly urging the resiliently mounted insulating blocks 44 toward the movable insulating block 43, while, upon the occurrence of an arc therebetween, the blocks 44 are urged laterally away from the movable blocks 43, the force causing the latter action depending to a large extent upon the magnitude of the current in the arc. If the current in the circuit-interrupting arc is small in magnitude, the lateral movement of the blocks 44 against the bias of the springs 45 is also small; if the current is large in magnitude, the lateral movement is greater; but for every value of cur-. rent in thecircuit-interrupting arc, the width of the arc space is controlled by a balance between the lateral outward action due to the arc and the inward bias of the springs. As a result the voltage gradient through the device tends to maintain a constant value as measured in terms of voltage drop per unit length of arc, regardless of the current through the arcing contact structure. It is thus possible, through the use of proper materials and dimensions in our device, to either reduce the current in a circuit connected through our device, or to stretch the arc within the arcing contact structure beyond its critical length for the conditions.

While in the above description of our invention, Y

we have explained the operation of our device through a downward movement of the operating rod 33, it will of course be clear that an upward movement of this rod also recloses a circuit through the device. The short length of travel required between the upper pair and the lower pair of arcing contacts permits the movable arcing contact member to be moved between these contacts in either an upwardor downward direction in such a short time that users of electrical energy supplied by a transmission line connected through our device are disconnected from the supply for only from one-thirtieth to one-fifteenth of a second, when a commonly used operating rod speed is employed in connection with our circuit controller. In a circuit-controller embodying our invention, and for use on 13 kv., 60 cycle distribution circuits, we have found that an interval of 1.7 cycles is required for parting the arcing'contacts, and 2.25 cycles for reclosing the circuit. It is of course desirable that the arcing time be not less than cycle on an alternating current system, as the arc is most readily extinguished when the instantaneous value of the current is zero. The above reclosing time is much shorter than that possible through the use of any available circuit-reclosing devices which we have been able to discover, and is made possible through the novel construction of the arcing contact structure in our device.

The construction of our device as described. in this embodiment of our invention may be otherwise modified without departing from the spirit of the invention.

We claim as our invention:

1. A circuit controlling device comprising, in combination, an arcing contact structure including a pair of resiliently mounted insulating bodies supported in spaced relation, an upper pair and a lower pair of resiliently biased contacts extending in spaced relation through said resiliently mounted insulating bodies, a movable member of said arcing contact structure adapted for a first downward movement and a second downward movement, said movable member including an insulating body rigidly attached to a non-conducting control rod and having a resilient contact member of conducting material extending therethrough adjacent the midpoint thereof and adapted for movement between said resiliently mounted insulating bodies to engage either the upper or the lower pairs of contacts to close a circuit, the first movement first elongating the circuit-interrupting are between and'along adjacent faces of said resiliently mounted and said movable insulating bodies, and finally closing the circuit through the engagement of said resilient contact member with said lower pair of resiliently biased contacts, the second movement first elongating the circuit-interrupting are between and along adjacent faces of said resiliently fixed and said movable insulating bodies and finally mechanically actuating a means including a bar of insulating material having a plurality of contacts rigidly mounted near each end and supported by a pair of resilient main contact clips for disconnecting said arcing structure from the circuit.

2. A circuit-controlling device comprising a housing, elements constituting a main current carrying switch, an arc suppressing switch, a main disconnecting switch and an auxiliary disconnecting switch all contained within said housing, a control member associated with said elements, said control member being arranged to mechanically actuate said switches, and means responsive to a predetermined longitudinal movement of said control member for actuating only said main current carrying switch and said arc suppressing switch.

3. A circuit-controlling device comprising an arc suppressing switch, an auxiliary disconnecting switch and a main disconnecting switch, a movable control member common to al the switches,

and means responsive to a predetermined longitudinal' movement of said control member for serially connecting all of said switches.

4. A circuit-controlling device for an electrical circuit comprising a housing, elements constituting a main current carrying switch and an arc suppressing switch all contained within said housing, said device having a normally closed position in which said are suppressing switch is shunted by said main current carrying switch, said arc suppressing switch including upper and lower contacts, a bridging member arranged to engage either said upper or lower contacts to connect said circuit, a movable control rod associated with said elements, and means responsive to a predeter-' mined downward movement of said control rod from said normally closed position for opening said main currentcarrying switch and engaging said bridging member with said lower contacts.

5. A circuit-controlling device for an electrical circuit comprising a main current carrying switch, a main disconnecting switch, an auxiliary disconnecting switch and an arc suppressing switch, a movable control rod combined with the switches, said are suppressing switch including upper and lower contacts, elements of insulating material associated with said contacts, a bridging member carried by said control rod for engaging either said upper or lower contacts, the arrangement being such that the circuit-interrupting arc is elongated between the adjacent faces of said elements of insulating material upon a first downward movement of said control rod from a position in which al of said switches are closed, means responsive to said first movement for initially opening said main current carrying switch and said are suppressing switch and connecting said main disconnecting switch and said arc suppressing switch in serial relation with said circuit, and for finally reclosing said circuit through the engagement of said bridging member with said lower contacts.

6. A circuit-controlling device comprising a main current carrying switch, a main disconnecting switch, an auxiliary disconnecting switch and an arc suppressing switch, a movable control rod common to all the switches, cooperating contact members associated with said main disconnecting switch, and means including said contact members for maintaining said auxiliary switch in closed position while permitting actuation of said main current carrying switch and said are suppressing switch by a movement of said control rod.

7. A circuit-controlling device'comprising an arc suppressing switch, an auxiliary disconnecting switch, a main disconnecting switch and a main current carrying switch normally in shunt with said'arc suppressing switch, said auxiliary disconnecting switch being interposed between said main disconnecting switch and said arc suppressing switch, a movable control rod common to all the switches, said arc suppressing switch including juxtaposed elements of insulating material, upper and lower contacts extending through said elements and a bridging member arranged for movement between said contacts in response to a reciprocatory movement of said control rod for providingitwo closed circuit positions of said are suppressing switch, said reciprocatory movement actuating said main current carrying switch and elongating the circuit-interrupting arc in a space between the adjacent faces of said insulating elements whereby to extinguish it, cooperating contact members associated with said main disconnecting switch, and means including said contact members for maintaining said auxiliary switch in closed position during such reciprocatory movement.

8. A circuit-controlling device comprising an arc suppressing switch, an auxiliary disconnecting switch and a main disconnecting switch, a movable control rod common to all the switches, means responsive to a longitudinal movement of said control rod for initially serially connecting all of said switches and subsequently mechanically opening said switches in-the above-named order.

9. A circuit controlling device comprising a housing, elements constituting a main current carrying switch, an arc suppressing switch, a main disconnecting switch and an auxiliary disconnecting switch all contained within said housing, a movable control member associated with said elements, and means responsive to a predetermined downward movement of said control member for actuating only said main current carrying switch and said are suppressing switch, and to a continued downward movement for actuating said are suppressing switch, said auxiliary disconnecting switch and said main disconnecting switch.

10. A circuit-controlling device comprising an arc suppressing switch, an auxiliary disconnecting switch, a main current carrying switch and a main disconnecting switch, a movable control rod common to all of the switches, said device having a normally circuit-closed position in which the switches are so related that said main current carrying switch is in shunt relation with a series arrangement of said auxiliary disconnecting switch and said arc suppressing switch, and said main disconnecting switch is in series circuit relation with the group comprising all the other switches, means responsive to a first longitudinal movement, of said control rod for opening said main current carrying switch and connecting the remainder of the switches in serial relation, and means responsive to a second movement of said control rod in the same direction as said first movement for opening all of said switches.

11. A circuit-controlling device for an electrical circuit comprising a main current carrying switch, a main disconnecting switch, an auxiliary disconnecting switch and an arc suppressing switch, a movable control member common to all of the switches, means responsive to an initial downward movement of said control member for mechanically actuating only said main current carrying switch and said are suppressing switch, and to a continued downward movement for mechanically actuating said main disconnecting switch, the switches being so combined that the latter movement completely isolates from the circuit all of the elements of said main current carrying switch and said arc suppressing switch.

12. A circuit-controlling device for an electrical circuit comprising a main current carrying switch, a main disconnecting switch, an auxiliary disconnecting switch and an arc suppressing switch, a movable control rod common to all of the switches, said control rod having a first position, a second position and a third position, the cooperation between said control rod and said switches being such that in the first position all of said switches are closed; in the second position said main current carrying switch is open and the remainder of said switches closed, and in the third position all of said switches are open.

13. In a switching device, a housing, insulated conducting line terminals extending through openings in said housing, a plurality of switches including a main disconnecting switch all contained within said housing, said main disconnecting switch including male contact members rigidly secured adjacent the respective ends of a bar of insulating material, female contact members carried by said line terminals, said female contact members being arranged for cooperation with said male contact members to 'detachably support said bar of insulating material for maintaining said main disconnecting switch in closed position, a control rod common to all the switches,

a passageway vertically through said bar of insulating material for permitting a reciprocatory movement of said control rod therethrough whereby certain of said switches may be actuated independent of said main disconnecting switch, and means carried by said control rod for engaging said bar of insulating material following a predetermined movement thereof for actuating said main disconnecting switch.

RALPH R. PITTMAN. CARROLL H. WALSH. 

